1. Field of the Invention
The present invention relates to a grinding apparatus and a method for manufacturing a magnetic recording medium using the said apparatus. More particularly, it relates to a grinding apparatus suitable for manufacturing a low-noise and high-density magnetic recording medium and a method for manufacturing a magnetic recording medium using the said apparatus.
2. Description of the Related Art
Magnetic tapes made by applying a magnetic paint containing ferromagnetic powder and a binder have been used widely as magnetic recording media for audio and video systems, broadcasting, computer backup, and the like. In manufacturing such magnetic tapes, minute protrusions etc. on the surface of magnetic layer are sometimes removed by applying a grinding wheel such as a diamond wheel to the magnetic layer of magnetic tape (grinding) for prevention of wear of magnetic head, restraint of dropout, reduction in error rate, etc. (for example, Japanese Patent Application Publication No. 62-172532).
To manufacture such magnetic tapes, an apparatus is used which has a configuration such that a wide band-shaped magnetic tape material wound in a roll shape is cut into a plurality of narrow magnetic tapes with a slitter while being transferred, the magnetic tape is ground by a grinding wheel such as a diamond wheel, and subsequently the magnetic tape is wound up into a roll shape.
FIG. 6 is a schematic view in which the surfaces of magnetic layers of magnetic tapes 1, 1 . . . are ground by a grinding wheel 2. Conventionally, the grinding operation has been performed by windingly applying a plurality of (for example, forty) magnetic tapes 1, 1 . . . with a predetermined width (for example, 12.65 mm in width) to the cylindrical grinding wheel 2 having a predetermined length (for example, 1 m) as shown in FIG. 6.
However, such a grinding operation has a problem in that the grinding force of the grinding wheel 2 decreases gradually. The cause for this phenomenon of decreased grinding force is thought to be loading of grindstone caused by additives such as a binder component of magnetic layer, transferred objects of back layer, chips produced when the magnetic tape material is cut, shavings removed by grinding, and the like. If loading of grindstone occurs, the grinding force of grinding wheel for grinding the magnetic layer becomes nonuniform, and the quality of manufactured magnetic tape becomes unstable. In particular, in the case where the band-shaped magnetic tapes being transferred are ground continuously, a variation in the grinding force of grinding wheel causes a problem of the quality of magnetic tape that varies in the transfer direction of magnetic tape.
As a solution to this problem, conventionally, when loading of the grindstone of grinding wheel occurs, the grindstone surface is wiped off with a cloth etc. soaked with a solvent etc. capable of dissolving the magnetic paint to eliminate the loading of grindstone. This method has achieved a degree of effect.